The invention concerns a binocular telescope, especially a prism binocular.
Prism binoculars differ from terrestrial binoculars in their shorter construction. The binocular, in accordance with the invention, also shows the known assemblies. These include, among others, a focus adjustment which, as an example, may be embodied as an example in the form of a central drive to adjust both eye-piece lens slides or also diopter focusing mounts. The binocular in accordance with the invention shows, preferentially, both devices which has the advantage that spectacle wearers who do not wear their spectacles while using the binocular can dispense with their spectacles with the aid of the diopter focusing mount.
Such binoculars have, in their known designs, a predetermined magnification which is often six, seven, eight or ten times. The user adjusts such a binocular taking into account its depth of field to a specific large distance, which, for example, is 150 m. He then moves the diopter adjusting mount until he obtains a sharp image. By turning the central drive, he can reach all focus areas without the use of spectacles. However, he cannot change the magnification with such binoculars.
There are, any event, also known binoculars of the appropriate type which permit the user to change magnification. These include a design which, through the turning of a revolving head bearing different eyepieces, turns the two eye-piece lenses of the binoculars and therefore changes the magnification. Since the entire lens system of each eye-piece must be changed, this results in a substantial technical expense for the optics of the binoculars. Further, there arise unusual shapes different form customary design, which are often found to be bothersome.
Another possibility of the optional change in magnification by the user is offered by so-call zoom binoculars. In this case, the eye-piece system consists of several lenses and a handle with which a lens or a pair of lenses can be adjusted in the lens system, as a result of which the magnification of the binoculars is changed. In general, however, the quality of the image is deteriorated if it is compared with the binoculars indicated above which have a fixed magnification.
The invention is based on the problem of producing a pair of binoculars which provides the user with the possibility of choosing the magnification of the binoculars without difficulty, and without a design which is different from the customary design, or which substantially deteriorates the image quality.